1. Field of the Invention
The present invention relates to a media dispenser and, more particularly, to a media sensing method of a (small) media dispenser capable of discriminating various media and accurately discriminating whether a media is normal.
2. Description of the Background Art
Currently, as information communication technologies are developed, a cash dispenser can perform diverse foreign currency processing work as well as a banking work such as money deposit or money withdrawal.
FIG. 1 is an exemplary view showing a construction of a general media dispenser.
As shown in FIG. 1, the general media dispenser includes a first convey path 40 formed at a front side of a cassette that can receive media such as a bill or a check and conveying bills discharged by a discharge roller 30 by means of a convey belt, and a second convey path 50 branched from the first convey path 40 and discharging bills by means of a convey belt. In addition, a retrieval path 60 branched from the first convey path 50 and retrieving an abnormal bill is formed by a convey belt.
In order to forwardly rotate or reversely rotate the convey belt, there is provided a drive motor 10 for rotating a drive roller 20. And in order to selectively convey a bill to the second convey path 50 or the retrieval path 60 from the first convey path 40, there is provided a gate unnumbered which is operated by solenoid.
At the front surface of the discharge roller 30, there are provided a sensor 71 for sensing a discharged bill, a sensor 72 for sensing a bill being conveyed on the first convey path 40, a sensor 73 for sensing a bill conveyed on the second convey path 50, a sensor 74 for sensing a bill being retrieved due to a bill-overlap occurrence on the retrieval path 60, and a control board 80 for checking whether each sensor is normal and controlling driving of each part when a bill discharge command is received by a client's request.
A bill sensing method of the media dispenser constructed as described above will now be explained.
FIGS. 2A to 2D illustrate cases that bills are normally or abnormally sensed for a bill discriminating factor.
With reference to FIG. 2A, if two bills overlap, the detected width is longer than a normal case, so the discharged bill is considered to be abnormal.
With reference to FIG. 2B, the distance between a currently discharged bill and the next discharged bill is measured, and if the distance is smaller than the normal case, the discharged bill is considered to be abnormal.
With reference to FIG. 2C, a tilt of the bill is measured, and if the bill is tilt, the bill is considered to be abnormal.
With reference to FIG. 2D, the thickness of bills, and if two bills overlap, the discharged bill is considered to be abnormal.
As shown in FIGS. 2A to 2D, the media dispenser uses various sensors to discriminate whether the bill is normal. For instance, an RVDT (Rotary Variable Differential Transducer) sensor determines a thickness of a bill according to a difference value between a sense signal value of the RVDT sensor obtained as a sensing unit of the RVDT sensor is lifted up after the bill is conveyed and a pre-set sense signal value. Feed sensors are installed at a left side and a right side in the media dispenser to discriminate a width of the bill. A distance sensor measures a distance between bills. A skew sensor discriminates whether a bill is skewed. Through the plurality of optical sensors, it is discriminated whether a bill is normal.
FIG. 3A illustrates a waveform of a media thickness detect signal detected through the general media dispenser.
As shown in FIG. 3A, the control board 80 of the media dispenser compares a level of a bill thickness detect signal detected by the RVDT sensor with a pre-set reference range signal level. That is, the reference range signal level is compared with a single upper signal level and a single lower signal level. For example, if a bill thickness detect signal (A) included in the reference range signal level is detected, it is determined that one bill is being normally discharged. If a bill thickness detect signal (B) going beyond the reference range signal level is detected, it is determined that one or more bills are being abnormally discharged and the currently discharged bills are discharged to an internal retrieval box.
FIG. 3B illustrates a waveform of a bill width detect signal detected through the general media dispenser.
As shown in FIG. 3B, while a bill is being conveyed along the convey path having the feed sensor, a voltage value of a light receiving part of the feed sensor continuously maintains 0V until the bill passes, and then converted into +5V after the bill passes. Thus, the length of the bill is measured by measuring a time at which the voltage value is converted from +5V to 0V. And then, the level of the bill width detect signal detected by the feed sensor is compared with the pre-set reference range signal level, and if a bill width detect signal (C) going beyond the reference range signal level, it is determined that one or more bills are being abnormally discharged and the currently discharged bills are discharged to the internal retrieval box.
The media dispenser performs a media discrimination with various bill thickness ranges (0.06˜0.17 mm) of many countries. That is, since a bill thicker than 0.20 mm does not exist, measurement and discrimination of the bill are performed only in the case of the thickness of below 0.20 mm. Therefore, the conventional media dispenser can not be applied to various multi-media each having a certain range.
In addition, in the conventional art, a normal bill and an abnormal bill are discriminated by comparing a fixed range value for width and thickness of a bill and a range value measured by the sensor.
However, the measured actual width and thickness values of a bill may vary depending on a deflection occurring when setting a sensor and an environment condition. For example, there may occur a mechanical error in the RVDT sensor which measures the thickness of a bill. In addition, due to the specific characteristics of the bill, the measure thickness value can be higher at a low temperature and low moisture compared to a room temperature, and conversely, it is lower at a high temperature and high moisture due to the opposite phenomenon. The conventional art fails to solve these problems.